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![](https://rs.olm.vn/images/avt/0.png?1311)
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B = − 418 − − 218 − − 118 − − 318 + 2012 = − 418 − − 218 − − 118 + 318 + 2012 = − 418 − − 218 − 200 + 2012 = − 418 − − 218 − 2212 = − 418 − − 2430 = − 418 + 2430 = 2012.
![](https://rs.olm.vn/images/avt/0.png?1311)
A= - 418 - {-218-[-118-(-318)+2012]}
A= - 418 - {-218-[-118-(-318)+2012]}
A= - 418 - {-218-[-118+318+2012]}
A= - 418 - {-218+118-318-2012}
A= - 418 + 2018 - 118 + 318 + 2012
A= 1600 - 118 + 218 + 2012
A= 1582 + 218 + 2012
A= 1800 + 2012
A= 3812
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-418-\left\{-218-\left[-118-\left(-318\right)+2012\right]\right\}\)
\(=-418-\left\{-218-\left[-118+318+2012\right]\right\}\)
\(=-418-\left\{-218-\left[100+2012\right]\right\}\)
\(=-418-\left[-218-2112\right]\)
\(=-418-\left(-2330\right)\)
\(=-418+2330\)
\(=1912\)
-418-{-218-[-118-(-318)+2012]}
=-418-{-218-[-118+318+2012]}
=-418-{-218-[200+2012]}
=-418-{-218-2212}
=-418-(-2430)
=-418+2430
=2012
Tính giá trị các biểu thức sau:
a) A = 31 – 26 – 209 + 35
b) B = − 418 − − 218 − − 118 − − 318 + 2012
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
A = 31 – 26 – 209 + 35 = 31 – 26 – 209 + 35 = 31 − 26 − 244 = 31 − − 218 = 31 + 218 = 249.
b)
B = − 418 − − 218 − − 118 − − 318 + 2012 = − 418 − − 218 − − 118 + 318 + 2012 = − 418 − − 218 − 200 + 2012 = − 418 − − 218 − 2212 = − 418 − − 2430 = − 418 + 2430 = 2012.
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (326 - 43) + (174 - 57)
= 326 - 43 + 174 - 57
= (326 + 174) - (43 + 57)
= 500 - 100
= 400
b) (351 - 875) - (125 - 149)
= 351 - 875 - 125 + 149
= (351 + 149) - (875 + 125)
= 500 - 1000
= -500
c) - 418 - (-218 - (-118 - (-318 + 2012)))
= -418 - (-218 -(-118 + 318 - 2012))
= -418 - (-218 + 118 - 318 + 2012)
= -418 + 218 - 118 + 318 - 2012
= -2012
d) (-2) + 7 + (-12) + 17 + ... + (-52) + 57
= 5 + 5 + ... + 5
= 5.12
= 60
e) (-30) + (-29) + ... + 48 + 49 + 50
= 31 + 32 + ... + 49 + 50 (20 số hạng)
= \(\dfrac{\left(31+50\right).20}{2}\)
= 810
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-418-\left\{-218-\left[-118-\left(-318\right)+2020\right]\right\}\)
\(=-418-\left\{-218-\left[200+2020\right]\right\}\)
\(=-418-\left\{-218-2220\right\}\)
\(=-418+218-2220\)
\(=-200-2220\)
\(=-2420\)
![](https://rs.olm.vn/images/avt/0.png?1311)
cái này thì bấm máy tính hết đi:
a/2012
b/ -1+-1+......+-1(có 50 cặp)=(-1)*50=-50